/Engine/Plugins/Online/OnlineSubsystem/Source/Public/Interfaces/OnlineIdentityInterface.h
Obtain list of all known/registered user accounts
info about the users if found, NULL otherwise
[TArray](API\Runtime\Core\Containers\TArray)< [TSharedPtr](API\Runtime\Core\Templates\TSharedPtr)< [FUserOnlineAccount](API\Plugins\OnlineSubsystem\FUserOnlineAccount) > > GetAllUserAccounts() const